The creature was designed by Neal Scanlan who revealed to Collider that it is made up of a giant animatronic puppet, and not computer-generated. According to him, there were two puppeteers inside the Thala-Siren. “The head opened a little bit, two puppeteers got inside, we put the head back up, and we sealed it with a prosthetic band that went around the side,” he explained.

The puppeteers inside the costume also worked on the “internal milk delivery system”. “The guys on the inside could see what was happening on the outside, through monitors and a walkie system that we had, and Mark literally walked up, bent down, and milked his sea-sow. It made a lovely tasting drink, by the way. It wasn’t as disgusting as it looked.”

rian johnson built a functional thala siren (teet and all!!) that weight 3/4th of a ton and helicoptered it into ireland just so mark hamill could do this pic.twitter.com/ag8NYvDd2C